NutriStack
Digoxin and St. John's Wort, a conflict.
St. John's Wort significantly reduces digoxin levels through potent P-glycoprotein induction. A landmark study showed that St. John's Wort reduced digoxin AUC by 25%, which can lead to loss of therapeutic effect and potential decompensation in heart failure patients.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
Same shape as the other 1,729 pairs in the public database.
From the interaction database
What the row says.
Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.
At a glance
- Substances
- Digoxin and St. John's Wort
- Pair type
- Conflict
- Evidence (highest tier)
- Strong
- Source citations
- 1 source
- Stack Score effect
- −10 to your Stack Score (per scored conflict row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Conflict · Strong evidence
Conflict
What is happening. St. John's Wort significantly reduces digoxin levels through potent P-glycoprotein induction. A landmark study showed that St. John's Wort reduced digoxin AUC by 25%, which can lead to loss of therapeutic effect and potential decompensation in heart failure patients.
Mechanism. St. John's Wort induces P-glycoprotein (MDR1) expression in the intestine and kidneys. Digoxin is a P-gp substrate, increased intestinal P-gp reduces digoxin absorption, and increased renal P-gp enhances digoxin secretion, together substantially lowering plasma digoxin concentrations.
Recommendation. Do not combine St. John's Wort with digoxin. The reduction in digoxin levels can lead to loss of rate control or worsening heart failure. If already taking both, consult your cardiologist before making changes.
Stack Score
How this pair moves the number.
Effect on the composite score
If both Digoxin and St. John's Wort are in the same stack, this pair applies −10 to your Stack Score (per scored conflict row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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